<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #box2{
            margin-left: 4px;
            margin-bottom: 4px;
            display: inline-block;
            color: darkgrey;
            font-size: 4px;
        }
        #box{
            display: inline-block;
            width: 0px;
            height: 0px;
            border: solid 4px;
            border-left-color: transparent;
            border-right-color: transparent;
            border-bottom-color: transparent;
        }
        #box3{
            background-color:lightgrey;
            width: 50px;
        }
    </style>
</head>
<body>
    <div id="box3">
        <div id="box2">上海</div>
    <div id="box"></div>
    </div>
    
    
</body>
</html>